Kinematic Responses of Lead-caulked Joints for Cast Iron Pipelines Subjected to Strike-slip Faulting

Buried cast iron pipelines are susceptible to damage at joints under fault movements. In this paper, a new three-dimensional soil-pipe continuum model for segmented pipelines undergoing fault rupture is introduced, in which both the nonlinear behavior of lead-caulked joints and post-peak softening behavior of dense sand are properly characterized. The rationality of the developed numerical model is validated against experimental results reported in the literature. Parametric analyses indicate that ignoring the strain softening behavior of soil would underestimate the maximum joint rotations, and the parameters of fault-pipe intersection angle, cast iron-lead adhesion, and burial depth play a notable role on the magnitude of joint kinematics. Numerical fault rupture analyses are then conducted for cast iron pipelines with nominal diameters ranging from 900 mm to 1,500 mm. Based on the numerical results, predictive solutions are developed for estimating the maximum axial translations and joint rotations under fault movements. The residuals of the proposed solutions are generally unbiased. The proposed solutions can be used to evaluate the maximum joint kinematics in terms of axial translations and joint rotations for large-diameter cast iron pipelines with lead-caulked joints undergoing strike-slip fault ruptures.